1. Field of the Invention
The present invention relates to an apparatus for producing a silicon carbide (SiC) single crystal by a solution growth method, and a method for producing the SiC single crystal by using the production apparatus and a crucible that is used in the production apparatus.
2. Description of Related Art
SiC is a thermally and chemically stable compound semiconductor. Due to its superiority to silicon (Si) in terms of band gap, breakdown voltage, electron saturation velocity, and thermal conductivity, SiC has been attracting much attention as a material for next-generation power devices.
A sublimation method has been most commonly used as a method for producing an SiC single crystal. However, the SiC single crystal produced by the sublimation method tends to cause defects such as a micropipe defect.
Another method for producing the SiC single crystal is a solution growth method. In the solution growth method, a seed crystal that is composed of the SiC single crystal is brought into contact with an SiC solution. The SiC solution refers to a solution that is prepared by dissolving carbon (C) in a melt of Si or an Si alloy. Then, a super-cooled condition of the SiC solution is created in the vicinity of the seed crystal to grow the SiC single crystal on a surface of the seed crystal.
The SiC single crystal obtained by the solution growth method has the reduced number of defects such as the micropipe defect. However, a growth speed of the SiC single crystal is lower in the solution growth method than in the sublimation method.
In order to increase the growth speed of the SiC single crystal that is produced by the solution growth method, Japanese Patent Application Publication No. 2006-117441 (JP 2006-117441 A), for example, discloses a method for producing the high-quality SiC single crystal at a high growth speed by uniformly supplying a solute to the seed crystal. In the above publication, a rotational speed of a crucible or the rotational speed and a rotational direction of the crucible are periodically changed.
Despite the above, a further increase in the growth speed has been desired.
In order to further increase the growth speed, a method for increasing a degree of supersaturation of carbon in the SiC solution is considered. If an increased amount of carbon is supplied to the vicinity of the seed crystal in the SiC solution, the degree of supersaturation of carbon can be increased.